Cuts to the Royal Marines would significantly undermine national security, MPs have warned.

There is speculation the Government could axe two specialist ships - prompted by "short-term Treasury bookkeeping" - which would leave the Royal Marines struggling to carry out a "substantial" amphibious landing, according to a Commons Defence Committee report.

Some 2,000 Marines - about 30% - would be cut if the plans are signed off, the MPs say.

HMS Albion and HMS Bulwark are "essential for landing personnel, heavy equipment and supplies on a beach" and "their disposal would remove any prospect of the Armed Forces achieving a successful amphibious landing with a substantial force", says the report.

They can deploy smaller landing craft loaded with equipment and Royal Marines for a coastal assault.

Image:HMS Albion is one of the two specialised ships at risk

Other ships touted as possible replacements, such as aircraft carriers, are no substitute, it is claimed.

The committee adds: "Every other major defence power is seeking to increase its amphibious capabilities at the very time that the UK may be forced prematurely to abandon them."

The Royal Marines have already seen their numbers drop from 7,020 to 6,580 since 2011.

"Given the disproportionate contribution the Royal Marines make to defence and the sheer range and versatility of their military skills, both they and the country's security would be significantly undermined," the report says.

The leaked proposals are from the National Security Capability Review (NSCR), which the Defence Committee claims has been carried out behind closed doors without adequate input from experts.

Image:A Royal Marine landing craft births on HMS Albion during an exercise in 2010

It wants to question the National Security Adviser about the proposals - which it calls "drastic and dangerous".

Committee chairman Julian Lewis wants the Government to boost defence spending back to 3% of GDP.

He said he was assured by the defence procurement minister last January that the Albion and the Bulwark would be in service until 2033 and 2034.

The rethink shows "this is being forced on the Ministry of Defence by the Treasury", Mr Lewis said.

But some experts believe the Committee may be wrong to insist on keeping the ships.

Former Royal Navy officer Rear Admiral Chris Parry told Sky News: "They are right that we should preserve as many Royal Marines as we can - they are our primary elite forces and I think we are going to need them in the future.

"I don't think they are right about retaining the amphibious ships at all costs because the future operating environment will change."